Frequently, upon the loading of rail cars or other shipping vehicles or containers, voids remain between adjacent stacks of goods or between the stacks of goods and walls of the shipping containers. In order to prevent the load of goods from being damaged due to shifting during transit, void fillers, or dunnage devices as they are commonly referred to, are used to fill these voids. One such void filler commonly used is a honeycomb or cellular structure which is compressible into a short stack for storage and expandable into an elongated array for actual use. The cellular structure is typically manufactured from rectangular strips of sheet material, such as corrugated paperboard. Examples of this type of void filler may be found in U.S. Pat. Nos. 3,862,607, 3,842,757, 3,823,675, 3,618,535 and 3,593,671. Additionally, the void filler will have attached thereto a suspension member, with the ends of the suspension member extending laterally beyond the planar sides of the void filler. Examples of such suspension members may be found in U.S. Pat. Nos. 3,618,535, 3,593,671, 3,842,757, 3,862,607 and 3,823,675.
A major problem associated with the cellular-structured void fillers of the prior art is the so-called "hour glass" effect. When such a filler is suspended to extend downwardly under its own weight, the manner in which the void filler is attached to the suspension member tends to distort the upper and median portions, allowing the cells to either elongate excessively in a vertical direction or to sag about an axis normal to the facing of the cellular void fillers. The result is that the void filler assumes an hour glass shape, thereby creating voids into which the load of goods may shift. Additionally, such excessive distortion may cause the lower portion of the void filler to distort and retract, such that the overall vertical drop of the void filler may be reduced by up to 20% or more. As a result, excess material must be used in the manufacture of the cellular void filler in order to maintain adequate void filling capacity.
Numerous suggestions have been proposed in the prior art to alleviate the "hour glass" problem. In U.S. Pat. No. 3,593,671, transverse rigid members in certain of the cells were proposed to limit their horizontal contraction and prevent the honeycomb structure from sagging unduly. In U.S. Pat. No. 4,007,309, it was proposed to replace some of the freely foldable strips of material normally used to form the honeycomb with relatively stiff strips to resist undue vertical elongation of the cells of an expandable honeycomb structure. U.S. Pat. No. 4,349,303 discloses a suspension system comprising spaced, elongated, rigid suspension members which are woven through the upper two layers of the structure. The ends of the suspension members project laterally past the planar sides of the structure and are adapted to rest on the tops of articles of freight on opposite sides of the space filled by the load spacer. In U.S. Pat. No. 4,372,717, an intricate cellular void filler is disclosed wherein a plurality of horizontal cell rows, each containing a central diamond-shaped cell straddled by a pair of square-shaped cells, are stacked in vertical relation. Vertically adjacent corners and apexes of the cells are interconnected so as to allow vertical expansion of the suspended cellular array under its own weight.
The devices proposed in the prior art to eliminate the hour glass effect all have one thing in common in that all involve intricate designs and construction of the basic honeycomb cellular-structured void filler. However, there continues to be a long felt need in the field of dunnage devices for a simplified, economical, expandable load spacer which eliminates the hour glass effect. Furthermore, there is a long felt need for a simplified, economical, expandable load spacer which reduces the amount of material required to manufacture the load spacer. Heretofore, the dunnage devices of the prior art have not fulfilled these needs.
Other U.S. patents relating to the general field of dunnage devices are U.S. Pat. No. 2,980,573 issued to Clifford, entitled "Ventilated Honeycomb"; U.S. Pat. No. 3,501,367 issued to Parker, entitled "Honeycomb Core Structure"; U.S. Pat. No. 3,700,522 issued to Wonderly, entitled "Process of Making Honeycomb Panels"; U.S. Pat. No. 4,130,682 issued to Lauko, entitled "Sound Absorbing Device"; and U.S. Pat. No. 4,300,864 issued to Liebel et al., entitled "Freestanding Honeycomb Load Spacer.